Tropical Storm CHAN-HOM Advisory Bulletin (JTWC)
WTPN33 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL STORM 14W (CHAN-HOM) WARNING NR 018//
RMKS/
1. TROPICAL STORM 14W (CHAN-HOM) WARNING NR 018
03 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
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WARNING POSITION:
110600Z --- NEAR 36.5N 142.0E
MOVEMENT PAST SIX HOURS - 255 DEGREES AT 13 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 175 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
100 NM SOUTHWEST QUADRANT
160 NM NORTHWEST QUADRANT
REPEAT POSIT: 36.5N 142.0E
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FORECASTS:
12 HRS, VALID AT:
111800Z --- 36.0N 138.2E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 24 HR POSIT: 275 DEG/ 13 KTS
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24 HRS, VALID AT:
120600Z --- 36.2N 134.9E
MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
VECTOR TO 36 HR POSIT: 275 DEG/ 10 KTS
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36 HRS, VALID AT:
121800Z --- 36.3N 132.3E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
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REMARKS:
110900Z POSITION NEAR 36.4N 141.0E.
11AUG26. TROPICAL STORM 14W (CHAN-HOM), LOCATED APPROXIMATELY 133
NM EAST-NORTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED WEST-
SOUTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS.
MINIMUM CENTRAL PRESSURE AT 110600Z IS 982 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 110600Z IS 25 FEET. NEXT WARNINGS AT
111500Z, 112100Z, 120300Z AND 120900Z.
REFER TO TROPICAL DEPRESSION 13W (PEILOU) WARNINGS (WTPN32 PGTW)
FOR SIX-HOURLY UPDATES.
REFER TO TROPICAL DEPRESSION 15W (FIFTEEN) FINAL WARNING
(WTPN34 PGTW).//
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Tropical Storm CHAN-HOM Forecast Advisory (JTWC)
WDPN33 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (CHAN-HOM) WARNING NR
018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 36.5N 142.0E
INITIAL INTENSITY: 40 KTS
GEOGRAPHIC REFERENCE: 133 NM EAST-NORTHEAST OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 13 KTS
SIGNIFICANT WAVE HEIGHT: 25 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 14W (CHAN-HOM) QUICKLY APPROACHING THE EASTERN COAST OF
HONSHU AS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC)
BELEAGUERED BY HIGH MIDLEVEL SHEAR AND SIGNIFICANT DRY AIR
ENTRAINMENT. ENVIRONMENTAL ANALYSIS REVEALS A HIGHLY UNFAVORABLE
ENVIRONMENT, CHARACTERIZED BY HIGH (30-35 KTS) VERTICAL WIND SHEAR
(VWS), COOL (23-24 C) SEA SURFACE TEMPERATURES (SST), DEEP LAYER
DRY AIR ENTRAINMENT, POOR EQUATORWARD OUTFLOW, AND LAND INTERACTION
ALONG THE WESTERN PERIPHERY OF THE STORM. 14W IS POLEWARD OF THE
KUROSHIO CURRENT AND HAS LOST THE OCEANIC SUPPORT IT PROVIDED. THE
LOW LEVEL CIRCULATION REMAINS INTENSE, DESPITE THE DEGRADING
ENVIRONMENT AND DETERIORATING APPEARANCE IN ANIMATED MSI. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE FULLY
EXPOSED LLCC. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS
ESTIMATES LISTED BELOW.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH
AND A DEEP UPPER LOW TO THE SOUTH
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T3.0 - 45 KTS
RJTD: T2.5 - 35 KTS
RCTP: T2.5 - 35 KTS
CIMSS SATCON: 51 KTS AT 110600Z
CIMSS ADT: 41 KTS AT 110700Z
CIMSS AIDT: 38 KTS AT 110700Z
CIMSS D-MINT: 40 KTS AT 110402Z
CIMSS D-PRINT: 35 KTS AT 110700Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
VWS: 30-35 KTS
SST: 23-24 CELSIUS
OUTFLOW: WEAK EQUATORWARD
OTHER FACTORS: DEEP LAYER DRY AIR ENTRAINMENT
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 14W IS FORECAST TO CONTINUE TRACKING
WEST-SOUTHWESTWARD WHILE IT REMAINS UNDER THE INFLUENCE OF THE STR
TO THE NORTH AND DEEP-LAYER LOW TO THE SOUTH, WHICH, IN
CONJUNCTION, ARE PRODUCING A TIGHT STEERING GRADIENT AND INDUCING
QUICK TRACK SPEEDS FOR 14W. LANDFALL IN HONSHU IS IMMINENT.
CHAN-HOM IS FORECAST TO SPEND LESS THAN 24 HOURS OVER LAND,
REEMERGING OVER WATER IN THE SEA OF JAPAN BETWEEN TAU 12-24 AND
REMAINING OVER WATER UNTIL DISSIPATING BY TAU 36. REGARDING
INTENSITY, 14W WILL CONTINUE GRADUAL WEAKENING UP UNTIL LANDFALL IN
HONSHU, AT WHICH POINT, THE ELEVATED TERRAIN IS EXPECTED TO SHRED
THE LOWER LEVEL CIRCULATION. CHAN-HOM IS FORECAST TO LIMP ITS WAY
BACK OVER WATER BEFORE TAU 24, BUT THE ENVIRONMENT WILL CONTINUE TO
BE HIGHLY UNFAVORABLE AND CHAN-HOM WILL BE UNABLE TO RECOVER FROM
THE SEVERE WEAKENING IT EXPERIENCED OVER THE MOUNTAINOUS TERRAIN.
MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGHOUT THE FORECAST PERIOD, SUPPORTING THE JTWC TRACK
FORECAST WITH HIGH CONFIDENCE. LIKEWISE, THE RELIABLE INTENSITY
AIDS ARE IN STRONG AGREEMENT IN STEADY WEAKENING THROUGH
DISSIPATION AT TAU 36. AS A RESULT, THE JTWC INTENSITY FORECAST IS
ASSESSED WITH HIGH CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
INTENSITY 00-72 HR: HIGH//
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